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Book/Report | FZJ-2016-03507 |
;
1977
Kernforschungsanlage Jülich, Verlag
Jülich
Please use a persistent id in citations: http://hdl.handle.net/2128/11699
Report No.: Juel-1437
Abstract: Integral values of heat transfer and pressure drop are reported. They have been gained from 5 tube banks in cross flow of different tube pitches and roughnesses. The experiments were conducted at Reynolds numbers 5 $\cdot$ 10$^{3}$ < Re < 10$^{6}$ with air and helium as experimental fluid on the outside of the tubes. Increasing artificially the roughness of the tubes a gain in heat transfer was achieved up to 50% compared to a tube arrangement of technically smooth tubes without increasing the flow resistance. Besides this the fraction of each tube row of the integral heat transfer coefficient of the bundle was measured. In comparison to an arrangement of smooth tubes the heat transfer of the first tube row was increased in relation to the following ones. Furthermore the artificial roughness of the tubes effected an equalisation of the velocity profiles behind the heat exchanger.
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